Pulping apparatus

ABSTRACT

A waste treatment tub having a cylindrical side wall, a perforated bottom wall and a rotor mounted on the bottom wall is provided with a baffle which extends across the tub in chord relationship to the circle defined by the cylindrical side wall. The chord-like baffle shifts the center of the vortex formed by the rotor to a position non-coincident with the axis of rotation of the rotor to improve cutting efficiency and also causes undisintegrated material to be flung inwardly, from whence it can be carried through the treating zone. When the rotor is of the type which is provided with pivotally mounted hammers or flails, the flow pattern which results from the use of the chord-like baffle reduces vibrations which may be caused by material collecting on the vanes of the rotor and the hammers or flails.

Seiiert 1 Mar. 27, 1973 1541 PULPENG APPARATUS 1,122,660 5/1956 France..24l/46.08

51 tzPt SiftM'ddlt ,Oh' [7 1 men f e er e er I e own w PrimaryExaminerRobert W. Jenkms 1 Assigneei The Black Claws" p y AssistantExaminerAlan I. Cantor Hamilton, Ohio Attorney-Marechal, Biebel, French& Bugg [22] Filed: Mar. 10, 1971 [57] ABSTRACT [21] Appl. No.: 122,809

A waste treatment tub having a cylindrical s1de wall, a perforatedbottom wall and a rotor mounted on the 1 4 1 bottom wall is providedwith a baffle which extends Clt t "B0" across the in chord relationshipto the circle [58] Field of Search ..241/46.1l,46.l7,46.08; defined bythe cylindrical side wall The chord4ike 259/8, 43, 44, 96; 162/261;259/23, 24 baffle shifts the center of the vortex formed by the rotor toa position non-coincident with the axis of References Cited rotation ofthe rotor to improve cutting efficiency and UNITED STATES PATENTS alsocauses undisintegr ated material to be flung inwardly, from whence itcan be carrled through the 3,592,444 7/1971 Arvanitakis ..259/44 Xtreating zone. When the rotor is of the type which is COWICS providedpivotally mounted hammers or flails 3,595,438 7/197l at m-241/46-08X theflow pattern which results from the use of the Cowles chord like b eI.educes vibrations y be FOREIGN PATENTS OR APPLICATIONS caused bymaterial collecting on the vanes of the rotor and the hammers or1121115.

1,038,974 8/1966 Great Britain ..259/96 822,143 10/1959 Great-Britain..241/46.11 2 Claims, 3 Drawing Figures Patented March 27, 19733,722,832

FIG-l l6 l8 20 I6 44 24 25 25 42 AMI l I I 38 INVENTOR PETER SEIFERT BYM M2, M4

ATTORNEY PULPING APPARATUS BACKGROUND OF THE INVENTION Pulping apparatuswhich incorporates a rotor rotatably mounted on a perforated bedplateextending across the bottom of the pulper tub has gained widespreadacceptance in the paper industry for repulping broke, wastepaper, etc.In apparatus of this type the rotational movement of the rotor causesthe paper placed in the tub together with water to be subjected to bothmechanical and hydraulic shear forces as the mixture of water and paperis circulated in a vortical pattern outwardly and upwardly along thewall of the treatment vessel and then downwardly toward the center ofthe vessel and the rotor. The hydraulic shear forces are generated bythe violent vortical flow patterns set up by the rotor, whereas thesurfaces of the rotor itself are primarily responsible for themechanical shear forces. Pulping apparatus of this general type is shownin detail in the U.S. Pat. to Vokes, No. 3,073,535.

More recently, pulping apparatus of this general type has been adaptedfor use in treating solid waste materials. For example, apparatus shownin application Ser. No. 861,778, filed Sept. 29, 1969, now Blakley etal. U.S. Pat. No. 3,595,488, treats a mixture-of solid waste materialsand a liquid such as water or the like and disintegrates the relativelyfragile portions of the solid waste to a particle size small enough tobe extracted with some of the liquid in the tub in slurry form throughthe perforations in the perforated bedplate. Relatively infrangibleportions of the solid waste, such as metal castings, pipes and the like,are withdrawn from the tub separately from the slurry of relativelyfrangible portions.

Whereas the rotor shown in the apparatus of U.S. Pat. No. 3,073,535depends primarily upon the rotor surfaces for mechanical shearingaction, the rotor disclosed in the above-noted copending application is.

further provided'with pivotally mounted hammers or flails attached tothe outwardly projecting vanes of the rotor which cooperate with adiscontinuous attrition surface to provide additional shearing action.

SUMMARY OF THE INVENTION The present invention represents an improvementover pulping apparatus of the type described above. In pulping apparatusaccording to the present invention, a baffie extends across the tub fromone portion of the side wall to another portion thereof andsubstantially parallel to the axis of rotation of the rotor. Thus, ifthe side wall of the pulper tub or vessel is substantially I cylindricalin cross-sectional configuration, the baffle in cross-sectionalconfiguration constitutes a chord to the circle defined by thecylindrical side wall on the pulper tub, and the baffie in effect formsthat portion of the wall of the tub connecting the ends of thecylindrically curved portion.

This chord-like baffle has the effect of moving the center of the vortexcreated by the rotor to a position noncoincident with the axis ofrotation of the rotor. This produces a much more violent circulation ofthe material being processed by the apparatus and provides moreefficient disintegration of the material. Thus, knots or balls ofundisintegrated material are flung inwards, from whence they can becarried through the pivotally mounted hammers or flails.

I BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view,partly in section, showing the apparatus of the present invention;

FIG. 2 is a plan view of the structure of FIG. 1; and

FIG. 3 is a somewhat diagrammatic plan view, similarto FIG. 2, butshowing the flow pattern induced in a tub provided with the baffie ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT As seen in FIG. 1, the apparatusof the present invention includes a treatment vessel or tub 10 having anupstanding, circular, cylindrical side wall 12. The upper end of theside wall 12 is turned inwardly to form an overhanging top lip 14 whilethe lower end of the side wall 12 is directed inwardly at an angle toprovide a substantially frusto-conical portion 16. A bottom wall,referenced in its entirely by numeral 18 extends across the bottom ofthe portion 16 of the side wall and is comprised of a series oftrapezoidally shaped bars 20 which are angularly disposed with respectto the radius of the circle defined by the side wall 12 and are spacedapart to define a discontinuous attrition surface 22, all as explainedin greater detail in the above noted copending application.

The bottom wall 18 also includes a perforated bedplate 24 having aseries of holes 25 defined therethrough of some preselected, usuallyuniform, size and spacing. Rotatably mounted just above the bedplate 24is a rotor 26 having outwardly projecting vanes or arms 28, each ofwhich has a leading edge 30 and a trailing edge 32. Hammers or flails 34are pivotally mounted on opposing vanes or arms and are beveled on theirouter, under surfaces complementarily to the opposing surfaces of thebars 20. Additionally, the bedplate 24 can be provided with angularlydisposed bars 36 fixed to its upper surface and adapted to cooperatewith oppositely extending bars, not shown, mountedon the lower surfaceof the motor 26.

A shaft 37 extends downwardly from the rotor and is received in abearing 38 mounted in a lower portion of the treatment vessel and drivenby a motor 40 for rotation in the direction shown by the arrow in FIG. 2of the drawings. Immediately beneath the perforated bedplate 24 achamber 42 is defined by the downwardly and inwardly extending wall 44.An opening from the chamber 42 is connected to the elbow connection 46,which in turn is connected to a pipe 48 leading downstream to furthertreatment stations. Similarly, the interior of the treatment vessel 10is provided with an outlet 50 for a purpose to be presently described,

the outlet 50 being located, as shown in FIG. 2, at a position betweenthe periphery of the rotor 26 and the curved portion of wall 12.

With the apparatus thus described solid material such as wastepaper,broke, solid waste material or the like, and a liquid medium such aswater, are dumped into the treatmentvessel where the solid materials aresubjected to a violent hydraulic and mechanical shear forces. Relativelyfrangible portions of the solid materials are disintegrated until theyare reduced in particle size to a dimension small enough to pass throughthe perforations in the bedplate 24, after which they are extracted witha portion of the liquid medium in slurry form into the chamber 42.Relatively infrangible portions of the solids are extracted, eithercontinuously or periodically, through the outlet 50 for furthertreatment.

In apparatus of this general type, the rotational action of the rotor 26will cause the liquids and solids contained in the tub to be flungoutwardly along the side walls then upwardly and inwardly toward thecenter of the tub where they fall by gravity back toward the center ofrotation of the rotor 26. In treatment apparatus according to thepresent invention, the substantially symmetrical vortex thus created ismodified by the introduction into the treatment vessel of a baffle 52which is mounted in the tub and extends upwardly from the lower portionof the frusto-conical section 16 of the side wall to an inwardlyprojecting brow 54 which is annularly disposed within the vessel 10. Thebaffle 52 thus forms in effect a planar portion of the inner side wallof the tub extending along the chord connecting the ends of theremaining portion of the circularly curved side wall 12, and the arcsubtended by this chord is of substantial angular extent, shown asapproximately 100.

Thus, with the apparatus of the present invention, rather than thesubstantially symmetrical flow pattern found in prior art pulpingapparatus, the flow pattern is modified, substantially as shown in FIG.3 of the drawings. As thus modified, the vortex created through theaction of the rotor is shifted, to the right as seen in FIG. 3, to apoint where the center of the vortex is noncoincident with the center ofrotation of the rotor 26. This causes knots or balls of undisintegratedmaterial to be flung inwards, from whence they can be carried throughthe pulper cutting zone by normal action and disintegrated to a higherdegree. Additionally, the resulting flow pattern reduces vibrations inthe treat ment vessel caused by solid materials hanging on the vanes orpivotally mounted hammers and flails. As a result, much more efficientdisintegrating action is obtained and the active life of the apparatusitself is appreciably lengthened.

While the form of apparatus herein described constitutes a preferredembodiment of the invention, it is to be understood that the inventionis not limited to this precise form of apparatus, and that changes maybe made therein without departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

1. Apparatus for pulping liquid suspensions, comprising a tub having asubstantially vertical side wall including a circularly curved portionof less than 360 and a substantially planar portion connecting the endsof said circularly curved portion, a rotor mounted in the bottom of saidtub for rotation on an axis substantially concentric with the center ofsaid circularly curved wall portion, means for driving said rotor tocreate a vortex in a liquid suspension within said tub, and the extentof the arc subtended by said planar wall portion being sufficient tocause the center of said vortex to shift from said rotor axis away fromsaid planar wall portion.

2. Pulping apparatus as defined in claim 1 further comprising meansdefining a discharge outlet for relatively infrangible solids located inthe bottom of said tub at a position between said rotor and saidcircularly curved wall portion,

* i I! i

1. Apparatus for pulping liquid suspensions, comprising a tub having asubstantially vertical side wall including a circularly curved portionof less than 360* and a substantially planar portion connecting the endsof said circularly curved portion, a rotor mounted in the bottom of saidtub for rotation on an axis substantially concentric with the center ofsaid circularly curved wall portion, means for driving said rotor tocreate a vortex in a liquid suspension within said tub, and the extentof the arc subtended by said planar wall portion being sufficient tocause the center of said vortex to shift from said rotor axis away fromsaid planar wall portion.
 2. Pulping apparatus as defined in claim 1further comprising means defining a discharge outlet for relativelyinfrangible solids located in the bottom of said tub at a positionbetween said rotor and said circularly curved wall portion.